DESCRIPTION: Currently there exists no laboratory methodology that can predict the clinical performance of Dental restorations. The long-range goal of this work is to develop models and improved diagnostic tools that can be used to predict the relative clinical life of resin retained ceramic restorations. In this work we posit that interface degradation between the restoration and remaining tooth contributes to ceramic fracture and thus clinical longevity. The proposed plan is designed to test the hypothesis by combining the use of a simple but unique physical fatigue model with fractographic methods, a novel nondestructive evaluation technique, and fracture mechanics based computer modeling. The application lays out a systematic engineering based approach to study this problem. The objective of Aim 1 is to experimentally test our hypothesis. The model we have proposed is unique in that it allows the simulated restoration to be subjected to cyclic loading in a manner that consistently initiates failures from the interface without the accumulation of surface contact damage. Mechanical and environmental fatigue factors will be considered. Microtensile and fractographic methods will be utilized to examine the extent of the interface degradation resulting from fatigue conditions and determine the validity of our hypothesis. In Aim 2 we plan to evaluate the potential use of adjunct non-destructive tests to evaluate our proposed hypothesis. State-of-the-art non-destructive ultrasound technology will be applied to the evaluation of the interface and compared with microtensile and fractographic data obtained in Aim 1. The non-destructive technique, if proven successful, has significant potential for future development as a clinical diagnostic tool. In Aim 2 we also plan to apply fracture mechanics based computer models to investigate the influence of interracial degradation on the structural integrity of all-ceramic restorations. Although the proposed model is simple it will provide the foundation for future development of more complex models as fatigue-life predictive tools. Completion of the proposed work should provide basic understanding of the process by which fatigue failure of ceramic restoration occurs and a clearer understanding of the true potential of the experimental and analytical approaches.